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| Understanding Heart Disease Heart disease is a very complicated subject, and there’s lots of information out there. This is a general overview, and I plan to devote future newsletters to expanding on the major issues brought up here. I’m also including lots of links, so you can get more information now. Why do we care? The leading cause of death in the United States is heart disease. That goes for men and women. About 25% of Americans have some form of cardiovascular disease (heart disease is one form of cardiovascular disease). Women start later than men, but begin catching up once they reach menopause. Cardiovascular disease can affect the heart, brain (strokes), kidneys (requiring dialysis) and limbs (causing intermittent claudication, sometimes requiring amputations). Heart, or coronary disease is the most common, and most lethal of these. About 80% of sudden deaths occur in people who did not even know they had heart disease. 1 in 3 heart attacks are “silent,” meaning the person did not know they were having a heart attack at the time. Silent heart attacks most commonly occur in people with high blood pressure or diabetes. Physiology of heart disease The heart pumps blood to move blood through the body. The coronary arteries supply the heart with oxygen rich blood. Coronary artery disease (CAD) happens when they become narrowed or blocked. This occurs when plaque collects in the artery wall and is called atherosclerosis. As the plaque builds up, the arteries narrow, and the blood flow is reduced. If the heart gets too little oxygen-rich blood, it will often cause pain in the chest. This tends to be worse when the person is exercising, as the heart needs to work harder to supply blood to the exercising muscles. Sometimes the plaque will rupture leading to a blood clot, leading to blocked flow. Then a heart attack results. We know that the same process that causes the coronary arteries to become blocked occurs all over the body. Therefore someone with heart disease will be at risk for stroke (cerebrovascular disease), kidney disease, and blockage in the legs (peripheral vascular disease). Fortunately, most medications that treat any of them will help them all. You can find general
information on heart disease at these sites: http://www.nhlbi.nih.gov/health/public/heart/index.htm#chol
http://www.emedguides.com/topics.jsp?guide_id=200 Who is at risk? As you might have guessed, pretty much everyone is at risk. Those at higher risk include people who are smokers, have high blood pressure, lipid abnormalities (such as high LDL cholesterol, low HDL cholesterol, high triglycerides), diabetes, and family members with heart disease. Heart disease also increases with increasing age. We will go through the risk factors individually. You can calculate your risk of having a heart attack in the next 10 years at this site: http://hin.nhlbi.nih.gov/atpiii/calculator.asp?usertype=pub Smoking What can I say; we all know it’s bad for us. In case you need some more convincing, here’s some more info. http://www.americanheart.org/presenter.jhtml?identifier=4545 High blood pressure (AKA hypertension) Blood pressure measures the force of blood pressing against artery walls. Blood pressure will go up during exercise, and will come down again at rest. Stress will also raise blood pressure. Over time, high blood pressure will cause artery walls to thicken and roughen, which makes plaque formation easier. Increased blood pressure is directly related to the risk of heart attack and stroke. For instance, we know that for every 2-3 points we decrease blood pressure, we get a 6-12% decrease in strokes. In addition, there is no threshold at which the risk remains stable. That means that the lower the blood pressure, the lower the risk. This has made it difficult to determine what the optimal blood pressure should be. Recently, a major organization came out with new, lower blood pressure recommendations. The JNC 7 blood pressure classifications are as follows: Normal less than
120/80 It should be noted
that these values apply to healthy adults; children and people with
heart disease, kidney disease, or diabetes require lower blood pressure
readings. Abnormal lipid levels Blood lipids are fatty substance in the blood. Cholesterol and triglycerides are forms of lipids we measure to asses risk for heart disease. The body needs some cholesterol to stay healthy, but too much can damage artery walls.
Three fourths of people with heart disease have some form of lipid abnormality. As with blood pressure, the recommended levels have been changing. Age, sex, and health are factored in. The NIH recently published new guidelines, which you can find here: http://www.nhlbi.nih.gov/guidelines/cholesterol/ Diabetes People with diabetes have a very high risk for heart disease. The risk of having a cardiovascular event (like a heart attack or stroke) in the future is the same for diabetics as for those who have had a heart attack or stroke in the past. Type II diabetes (or adult onset diabetes) occurs when the body does not respond normally to its own insulin. Insulin helps bring glucose (sugar) into the cells. Without adequate insulin, glucose remains in the blood stream, which can affect arteries, leading to heart disease. In addition, type II diabetics usually have lipid abnormalities consisting of low HDL, high triglycerides and mildly elevated LDL. These lipid abnormalities will usually precede elevated glucose levels by many years. Metabolic syndrome is often a precursor to diabetes. In addition to the above lipid abnormalities, there is often hypertension and central obesity (apple or big belly shape). Fasting (morning, pre breakfast) blood sugars are usually normal, but often will be elevated after eating. There is generally plenty of insulin in the blood stream, but the cells that require the insulin cannot utilize it properly. This is called insulin resistance. (For more info, try http://www.s2mw.com/heartofdiabetes/resistance.html). People with metabolic syndrome are at high risk for cardiovascular disease. Treatment for metabolic syndrome includes weight loss, exercise, following a low fat, diabetic diet, and medication for the lipid abnormalities and high blood pressure. More information
on diabetes and heart disease can be found at: Lifestyle changes Diet and exercise are important in preventing heart disease. Inactivity and being overweight contributes to insulin resistance. Diet will affect lipid levels and the ability for the body to process blood glucose. Obesity makes the heart work harder, and can contribute to high blood pressure. Here is a link on exercise http://www.americanheart.org/presenter.jhtml?identifier=4563 in relation to heart disease. Other factors There has been discussion about other markers for heart disease, including homocysteine levels and C-reactive protein (HS CRP). Elevated levels seem to be associated with heart disease, but we still don’t know if lowering the levels will lower that risk. Treatment will have to be dealt with in a future newsletter. (sorry) If this has you intrigued, you might want to sign up for new releases from the American Heart Association http://www.americanheart.org/presenter.jhtml?identifier=1200031. I hope this has helped you gain a general understanding of heart disease. This is an area of much research, and our understanding of the process is changing rapidly as more information comes in. I find it most interesting that many disease processes seem to be interrelated, which hopefully will assist us in treating this common and deadly illness. To your good
health,
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copyright 2006, Jasmine Moghissi, MD